Columbia Valley is having another round of poor air quality, according to the Northwest Clean Air Agency.

A monitor has detected air in the unhealthy range for fine particles in that part of Whatcom County. It has been an on-and-off issue all of November. Fine particles in the air can be harmful because inhalation can cause damage to delicate tissues.

"Unhealthy" is one of six categories used to describe air quality in the state: good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous.

The agency sent a notice to Columbia Valley residents on Monday, Nov. 26, asking them not to burn wood for heat or recreation during poor conditions.

Conditions are expected to improve by Thursday as winds and rain increase. In the evenings, though, air quality is often worse in the area because more people are home using wood stoves, and cold weather and nearby mountains can trap smoke close to the ground